A man-machine interface (MMI) is a communication tool between a user and an electrical system such as a computer or an embedded system. Through the MMI, a user can input instructions to control the electrical system, and the result is displayed after the instructions are executed by the electrical system. A mouse is one of the common input interfaces. A user can move a cursor accordingly on a screen by moving the mouse. However, the volume of the mouse is too large to be integrated into the embedded system directly. Therefore, a touch panel is developed to be a new generation of the MMI.
Both prior single-touch panels and recently developed multi-touch panels are designed to realize inputting instructions through pointing at an object. For example, there are many function options, such as a menu and a number keypad, displayed on the screen of a mobile phone, and a user can input a phone number by pointing at the corresponding number keypad in sequence on the touch panel of the mobile phone. However, the sensitivity of each touch panel to receiving a touch action varies. When the sensitivity is low, the user needs to press hard on the touch panel, and that shall put a burden on fingers after extensive utilization. On the contrary, when the sensitivity is too high, one is prone to accidentally point at a needless function option such that the touch panel becomes difficult to manipulate. Therefore, it is necessary to develop a design, which is different from the prior pointing operation, for raising the control accuracy for users.